JPH0121522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an automatic magnetic recording and reproducing apparatus for a magnetic recording and reproducing apparatus such as a tape recorder, which is capable of automatically and quickly setting the amount of recording bias applied to a magnetic tape. This invention relates to a recording bias amount setting method.

Magnetic recording and reproduction of audio signals in a tape recorder requires low distortion over a wide band and a wide dynamic range. When an audio signal is recorded on a magnetic tape as a recording medium, a bias current (high frequency current) is superimposed on the signal current to avoid the nonlinearity of the magnetic tape. In tape recorders, an important issue is where to choose the setting point for the bias current. By the way, there are different types of magnetic tape (normal tape,
The optimum recording bias current for a tape recorder is If different types of magnetic tapes are used while keeping the size constant (fixed), the optimum characteristics of each magnetic tape cannot be obtained. That is, in magnetic recording and reproduction in a tape recorder, it is necessary to set an optimal recording bias current according to the characteristics of each magnetic tape described above.

When setting the recording bias value, the following is a general method for detecting the optimal recording bias value.

(1) A method in which the recording bias amount is varied as a parameter and the recording bias value is set at a point where the recording playback level becomes flat between the reference frequency and high frequency.

(2) A method of varying the recording bias amount, determining the point at which the recording and playback level at a certain reference frequency peaks, and determining the optimal value as the recording bias value from this point.

Note that the above-mentioned variation in the amount of recording bias means that the recording bias is divided into steps (resolution) within a certain variable range. Usually, the resolution within the variable range of the recording bias described above is not changed depending on the type of magnetic tape used. That is, the above-mentioned resolution is the same regardless of the type of magnetic tape used. Therefore, no matter what type of magnetic tape is used, the time required to set the recording bias value is the same.

In the present invention, in the same type of magnetic tape (for example, normal tape type, metal tape type, etc.),
Focusing on the small amount of change in the appropriate recording bias amount, we changed the resolution depending on the type of magnetic tape used and minimized the overall bias variable range to find the optimal recording bias value in a short time. An object of the present invention is to provide an automatic recording setting method in a magnetic recording/reproducing device that can be set.

An embodiment of the method according to the present invention will be described below.

Figure 1 shows the resolution in the entire bias variable range T for all types of magnetic tape.
This shows the case where a test is performed to set the recording bias value using 16 steps. but,
For normal magnetic tape, 10
If the step number is set to the optimal recording bias amount,
Since the above-mentioned recording bias amount does not change much due to differences in individual magnetic tapes, the resolution in the bias variable range _T1 is changed to 8 steps as shown in Figure 2, and the overall bias variable range is narrowed and illustrated. Set the 6th step as the optimal recording bias value. In other words, compared to the case shown in Figure 1, the time required for eight steps of adjustment can be saved, and for normal magnetic tapes, the time required to set the optimal recording bias value can be reduced as much as possible. can do.

Note that for chromium-based and metal-based magnetic tapes, the bias variable range T is as shown in Figure 1.
The resolution in 16 steps is tested. In the present invention, the bias variable range described above is changed depending on the type of magnetic tape used, thereby reducing the time required to set the recording bias value.

As described above, the present invention provides an automatic recording bias amount setting method in a magnetic recording/reproducing apparatus, in which an adjustment signal is recorded and reproduced while changing the recording bias amount in predetermined steps, and an optimum recording bias amount is set. In this method, the variable range of the recording bias amount is changed by changing the number of variable steps depending on the type of magnetic tape, so depending on the type of magnetic tape, the time for automatically setting the recording bias amount can be shortened. .

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams for explaining a recording bias setting method in the present invention.

Claims (1)

[Claims] 1. In an automatic recording bias amount setting method for a magnetic recording/reproducing device, which records and reproduces an adjustment signal while changing the recording bias amount in predetermined steps, and sets the optimal recording bias amount, A magnetic recording and reproducing device is configured to change the variable range of the recording bias amount by changing the number of variable steps depending on the magnetic tape type, and to shorten the automatic setting time of the recording bias amount depending on the type of magnetic tape. Automatic recording bias amount setting method.